Screw propeller



Patented July 11, 1944 SCREW PROPELLER Albert Itupp, Berlin-Sudende,Germany; vested in th Alien Property Custodian Application October 4,1938, Serial No. 233,270 In Germany October 13, 1937 (Cl. I'm-1%) 3Claims.

This invention relates to screw propellers, intended especially foraircraft, in which the blades are mounted in the hub so as to beradially movable to give automatic centrifugal adjustment of the bladesand in which resilient means is provided resisting the action ofcentrifugal force to effect the adjustment-movement.

It is an object of the present invention to provide a device whichensures uniform adjustment of all the blades of the propeller.

Four embodiments of the'invention are shown by way of example in thedrawings, wherein:

Fig. 1 shows an embodiment of the invention in side elevation; and

Fig. 2 is a sectional sideelevation through another embodiment.

Figures 3 and 4 are sectional side elevations of other embodiments.

Similar parts in the different figures are designated by the samereference numerals.

Referring to the drawing:

Fig. 1 shows an embodiment in which uniform adjustment movement of theblades is ensured by a device comprising a lever. The blade roots I aremounted in the hub 2 in a known manner such that the blades can bycentrifugal force be moved lengthwise of the blade axes as well asturned about the blade axes to efiect diametral adjustment of the bladeswith simultaneous pitchadjustment. The hub 2 has the form of a simpletube which is open at both ends in order to receive the blade roots I.The hub 2 is provided at the drive side with a flange 2w by which thehub is connected with the engine shaft. The arrangement for producingthe pitch adjustment of the blades may consist in known manner ofhelical grooves 35 which are cut on the inner side of the tubular hub 2,and of pins 3| which are provided on the blade roots I and engage in thegrooves 3t. When the blades move radially they describe at the same timea rotational movement about their axes.

This arrangement for pitch adjustment is, however, not essential and canbe absent.

Provided at the ends of the hub 2 arelugs 2b which carry shafts(spindles or the like) I2, about which the single-armed levers II canswing, and which extend in a direction transverse the blades, that is,transversely to the longitudinal aXes of the blades. The levers I areloaded by (or sub ject to the action of) resilient means, for example atraction spring 8, at their freely projecting ends, and at a centralpoint of levers I i there are provided rollers I3 which press on theouter surfaces of the flanges Ic of the blade roots.

When the blades tend to move outwardly by reason of centrifugal force,the spring 9 tends to act oppositely to such movement.

In order that the movements of the two levers E I be always of uniformmagnitude, they are connected together by a movement-transmittingconnection. The connection may be a crank, a double-armed lever orequivalent arrangement. As a result of this connection, the diametraladjustments of the blades are also of equal magnitude when both bladesare moved outwardly as a result of centrifugal force.

Fig. 1 shows an embodiment in which a twoarmed lever l (i. e. a leverwhose arms are disposed on opposite sides of the levers pivot) isivotally supported outboard of the hub 2 on a bracket 8 on the hub. Thetwo-armed lever 1 is connected by links Ifl with single-armed levers H(i. e. levers Whose arms are disposed on the same side of the respectivepivots) which can pivot freely about a fixed pivot I2 on the hub 2 andbear through the intermediary of rollers 53 on the flanges to of theblade roots I. On movement of the blades lengthwise of the bladeaxes thelevers II are moved. By virtue of the two-armed lever l and the links IQwhich are connected to the lever I at equal distances from that leverspivot a uniform movement of the blades is obtained. The ends of thelevers II are connected together by a tension spring 9 and thisconstitutes means resisting centrifugal adjustment of the blades.

Fig. 2 shows an embodiment in which one of the blade roots I is providedwith a threaded nut I4 whereas the opposite blade root la is providedwith a complementary threaded stud or screw 15. The nut and stud havefixed connections with the respective blades. On movement of the bladesin the direction of the blade-axes the blade roots I and la. aresimultaneously turned about their axes by known means, viz: a key andfeather device (not shown but similar to the construction 3| of Fig. 1)In this way, the blades being interconnected by the bolt I5 and nut I4,the turning movements corresponding to longitudinal movements of theblades must be equal. The members It constitute parts of resilient meansresisting the centrifugal adjustment of the blades, the means beingessentially similar to those shown in 1.. The members i6 are, forexample, twoarmed levers adapted to swing about a fixed pivot tea on hub2 and which at their free ends are loaded by a pressure spring 35.

Fig. 3 shows an embodiment in which. the biade roots I are loaded bylevers I6 and springs H in a manner similar to that shown in Fig. 1.Links I8 of equal lengths are coupled to the levers I6 and are connectedto a slipper I9 which is guided in a slot or guideway 20 provided in abracket- 2fia, which is rigidly connected to the hub 2. On movement ofone lever I6 the slipper I9 is moved through the intermediary of thelinks I8 and pulls or pushes the other lever I6 by an equal amount.

The ends of the levers I6 which engage on the blade feet extend in anannular groove Ib which is formed at the foot of the blade. The ends ofthe levers I6 are thereby positively connected in both diametraldirections of movement of the blades therewith. Thus, if a blade is tobe held in the hub by clamping, while the other blade moves outwardlyunder centrifugal force, the clamped blade is also positively driven outwardly.

Fig. 4 shows an embodiment in which the device to ensure uniformadjustment movement is constituted by directly interengaging toothedsegments 2 I. These segments are, suitably, mounted on the pivots 22 ofthe levers I6. The gear segments are thus rigidly connected with thelevers I6 so that the levers I6 must always describe the same movements.The inner ends of the levers I6 engage in an annular groove lb of theblade roots I, so that the blades must always describe the same radialmovements. The outer ends of the levers I6 are loaded by a pressurespring IT. The hub 2 has the flange 2a, for connection to the engineshaft and 30, 3I designate means which, on radial movement of theblades, cause their rotation about the longitudinal aXes of the blades.The means 30, 3I can, however, be absent without limiting the scope ofthe invention.

It will be manifest that the uniform adjustment of all the blades isensured by virtue of the fact that the device comprises a member movablein a determinate path and connected to the respective blades in eachcase by positively acting movement-transmitting elements, that is tosay, elements which prevent relative play between the device and theblades.

I claim:

1. A screw propeller, including a hubhaving a driven side, a pluralityof blades mounted in the hub and movable outwardly under centrifugalforce to effect diametral adjustment of the propeller, a lever for eachblade to resist such outward movement, each lever having a pivot infixed relation to the hub and an arm projecting beyond the hub in adirection from the driven side of the hub, resilient loading meanscommon to all levers, each lever having a part to exert an inwardpressure on a part of a blade at the hub, and movement-transmittingelements connected each at one end to a lever arm beyond the hub and atthe opposite end to a common element-equalizing member carried by afixture projecting from the side of the hub remote from the drivingside.

2. A construction as defined in claim 1, wherein the commonelement-equalizing member acts in blade-compelling movement of one leverarm to compel simultaneous, similar, and equal movements of all otherlever arms.

3. A construction as defined in claim 1, wherein themovement-transmitting elements include a double-armed lever pivoted infixed relation to the hub and beyond the hub relative to the driven sidethereof, and equal-length links connecting the respective ends of thedouble-armed lever to the respective levers for the blades, the ends ofthe links connected to the levers for the blades being at equaldistances from the pivots of such levers.

ALBERT RUPP.

